Hi there!
I just felt like making a tutorial, so here comes:
Step 1First, I copy the template (usually from Jetabout) and paste it into the newly opened GIMP. I make my aircraft transparent by going to Layers -> Transparency -> Colour to Alpha. Result is like this:
Step 2I want my plane to look white again, so I add a background layer which is completely white:
Step 3I add my colours to the drawing on a new layer
below the aircraft layer, but
above the background layer. Please note that it doesn't matter if you paint outside the aircraft. Why is explained later on.
Step 4Note that I have to delete the painting around the windows, otherwise you would be able to see the colour through the windows. I usually do this when I'm finished with the painting to avoid retracing erased lines.
Step 5On a new layer I copy the logo provided with the request - or create my own. I make it fit so it looks nice, and if it overlaps a window, I repeat step 4.
Step 6I hide the logo and colour layers and add a new layer
above all layers except the aircraft layer. On this layer I will draw my shadows by using the Blending tool. Play around by selecting different transitions and shades of grey. Remember to use white as one of your two colours. Please note that the engine cowlings are on a layer each.
Step 7When you find the right shading make the layer transparent, then you will see this:
Step 8It still looks kind of flat, so I decide to use the Blending tool again (on a new layer), but this time to add a shine on the top of the aircraft. I select another transition, and I get this, which looks much better.
Step 9 - done!I still don't like how much of the aircraft has the same colour as the background, so I select the aircraft layer and fill out the area around the aircraft with a shade of blue. This will also automatically hide all previous errors (e.g. paint outside the aircraft), making the job look perfect.
Useful websites with templates:
Jetabout -
freewebs.com/jetabout/Skylite Design -
http://www.freewebs.com/sla31/apps/photos/I hope you find this useful. If you have any questions feel free to ask them. I will be glad to help you!